URGENT Exchange 2003 intermitently resends old emails

We have Exchange 2003 with all latest updates in Server 2003 domain. About a week ago our Exchange server started randomly sending out some old emails. Maybe 3-4 times a week. Very random and no pattern. We had also a situation when some email didn't reach the recipient causing some communication confusion in the company. The Exchange has been running OK for the past 3-4 years. Does this ever happen to anyone else and what could be reason and solution ?

You are welcome. The problem usually appears after restarting the store or the server (which of course restarts the store).

It is because of mail servers greylisting mail from your server and due to the bug, the emails do not get delivered and do not appear on your server to send. Once the patch is installed, the messages will reappear in your queue and can be re-sent, which is the aim of greylisting, forcing the sender to re-send as spammers only usually try to send the once.

All should be well - leave it a couple of days and restart the store or the server to hopefully show that all is well. Ideally if you can remember some email domains that suddenly re-appeared in the queue - try to send some messages to those domains.

You can also send me a test message to alan @ it-eye.co.uk as we also use greylisting.